Process for making cores and molds, articles made thereby and binding oil therefor



PROCESS FOR MAKING CORES AND MOLDS, ARTICLES MADE THEREBY AND BINDING OIL THEREFOR August Tobler, Windisch, near Brugg, Switzerland, and Karl-Paul Cassatt and Leon Schmit, Brussels, Belgium No Drawing. Application March 15, 1955 Serial No. 494,544

14 Claims. (Cl. 22-193) This invention relates to foundry cores and moulds and methods of making the same and particularly to nondeforming cold setting cores and moulds and a method of preparing such cores and moulds.

Large numbers of cores and moulds, both large and small, are used in foundry practice. One of the major problems in preparing such cores and moulds is the problem of binding them so that they maintain their integrity during preheating and when fitted together prior to casting and during the casting operation. Various types of binder materials have been proposed but, in general, no completely satisfactory non-deforming cold setting cores and moulds have been available. It has been the general practice to use drying oils, such as linseed oil, sunflower oil, grape seed oil and similar drying oils with the sand or other core forming or mould forming material. Such oils are used to form a thermoplastic film around the sand grains in an effort to hold the grains in position. Difiiculty has been experienced, however, because this film softens when the core or mould is baked in an oven, as is the general practice in forming cores and moulds prior to their use in receiving cast metal. As a result of this softening of the drying oils, the cores or moulds produced in this fashion tended to collapse or slump, or at least suffer some damage by reason of their own weight, resulting in a large number of unusable cores and moulds. It has also been proposed to use certain oils having conjugate lines of double bonding, such as wood oil, dehydrated castor oil, oiticica oil and the like. These oils will not permit the mould or core to collapse but they too, have disadvantages. The cores produced by using such conjugate double bonded oils are brittle, easily broken and very expensive.

The present invention provides non-deforming, cold setting cores and moulds which are free from the difficult es inherent in the moulds heretofore made. The present invention provides non-deforming cold setting cores and moulds made up of the usual mineral core forming material, such as sand, bound together with a bonding agent made up by combining and polymerizing triglycerides of three types, an oil having conjugate lines of double linking, a

such as wood oil, an oil having an acetylene type bond, such as Boleko oil and an oil of the triglyceride type, such as fish oils, linseed oil and the like not falling within the two foregoing groups. Preferably the oils are mixed and at least partially polymerized prior to their addition to the mineral core forming material, such as sand. Preferably, oxidizing accelerators, such as chlorites, carbonates, metallic oxides, lead acetates, calcium chlorite and the like are used to accelerate the polymerization and bonding of the mixed oils.

The method of carrying out this invention will be apparent from the following examples, showing certain preferred practices of the invention.

Example 1 Ten parts by weight of wood oil were mixed with twenty parts by weight of Boleko oil, fifteen parts by nited States Patent weight of sunflower oil and fifty-five parts by weight of seal oil. These mixed oils were polymerized at about between 250 and 280 centigrade until the viscosity of 3000 centipoise was reached. The resulting polymerized product was dried in the usual manner and mixed with dry medium grained silica sand in the proportion of two and one-half percent by weight of the polymerized product on the weight of the sand. The resulting composition was formed into cores and moulds in the usual manner.

Example 2 Thirty-five parts by weight of oiticica oil were mixed with seven parts by weight of Boleko oil, ten parts by weight of linseed oil and forty-eight parts by weight of herring oil. The resulting mixture of oils was polymerized at a temperature between about 230 and 280 centigrade until a viscosity of 2500 centipoise was reached. This quick-dried, polymerized product was then mixed with dry, fine grained silica sand in the proportion of three percent of polymerized product by weight on the weight of the sand. Sodium chlorite was then added as an oxidizing accelerator to the sand in the amount of one-tenth percent. Cores and moulds were formed in the usual manner.

The polymerization of the oils may be carried out in an oven or in any of the well-known methods of heating to polymerization. The final polymerization of the cores and moulds may be caused by blowing oxygen containing gas such as pre-warmed air over the cores and moulds.

Cores and moulds according to this invention may be prepared by using any of the well-known core forming materials, such as quartz or silica sand, zirconium oxide, refractory clays, granulated Carborundum and similar core and mould forming materials. In the binder material, we may use any of the oils having conjugate lines of double bond linkage, such as wood oil, oiticica oil, dehydrated castor oil and the like. The oil having acetylene type linkage is preferably Boleko oil but other oils, having this type of link, may be substituted. The triglycerides not falling within the two foregoing groups used in the binder may be drying, half-drying or non-drying oils and accordingly may include linseed oil, grape seed oil, sunflower oil and the like, fish oils, seal oil, herring oil and similar oils. In the binder, the oil having conjugate lines of double bond linkage should amount to not less than about two percent of the oil mixture and may be as much as about fifty percent. The oil having an acetylene type bond should preferably be not less than about ten percent. The triglycerides not of the acetylene type bond and not of the conjugate line of double bond type, may vary from about five percent to eighty-seven percent. It is, of course, obvious that the larger the percentage of this latter type of triglycerides, the softer the core will be and, on the other extreme, that the larger the percentage of oils with conjugate lines of double bond linkage, the harder and more brittle the bond will become. However, the cores produced using a binder within the foregoing ranges will be satisfactory and will not slump or be so brittle as to break up on mere touching, as was the case with the prior art cores and moulds.

While we have described certain present preferred practices and certain present preferred compositions, it will be understood that this invention may be otherwise embodied within the scope of the following claims.

We claim:

1. A process for the manufacture of non-deforming cold-setting cores and moulds by the steps of admixing at least about 2% of an oil having conjugate lines of double.

bond linkage, above about 7% of an oil having an acetyl ene type bond and the balance an oil compatible with the amnese 2. A process for the manufacture of non=deforming' cold-setting cores and moulds by the steps of admixing at least 2% of a triglyceride having conjugate lines of double bonds, above about 7% of a triglyceride havingan acetylene type bond and the balance at least one trigylceride which does not fall within the two preceding classes, at

least partially polymerizing said admixed triglycerides, admixing the polymerized triglycerides with a mineral core forming material, forming the resulting admixture and completing the polymerization of any unpolymerized oils.

3. A process as claimed in claim.2jwherein the triglyo erides arcpolyrnerized by heating. 1

4. A process as claimed in claim 2 wherein the triglycerides are polymerized by blowing an oxygen containing gas over the admixture.

5. A process for the manufacture of non-deforming cold-setting cores and moulds by the steps of admixing at least about 2% of a triglyceride having conjugatelines of double bonds, above about 7% of a triglyceride having an acetylene ty e bond and the balance at least one triglyceride which does not, fall within the two preceding classes, admixing the mixture of triglycerides with a mineral core forming material, forming the resulting admixture and polymerizing the triglycerides.

6. A process for the manufacture of nondeforming cold-setting cores and moulds by the steps of admixing at least about 2% of a triglyceride having conjugate lines of double bonds, above about 7% of a triglyceride having an acetylene type bond and the balance at least one triglyceride which does not fall within the two preceding classes, partially polymerizing the admixed triglycerides, admixing the partially polymerized triglycerides with a mineral core forming material, forming the resulting admixture and completing the polymerization.

7. A process for the manufacture of non-deforming cold-setting cores and moulds by the steps of admixing at least about 2% of a triglyceride having conjugate lines of double bonds, above about 7% of a triglyceride having an acetylene type bond and the balance at least one triglyceride which does not fall within the two preceding classes, partially polymerizing the admixed triglycerides, admixing the partially polymerized triglycerides with a mineral core forming material, and an oxidation accelerator, forming the resulting admixture and completing the polymerization.

8. A process for the manufacture of non-deforming cold-setting cores and moulds by the steps of admixing above about 10% of Boleko oil, at leastabout 2% of at least one oil selected from the group consisting of wood oil, oiticica oil and dehydrated castor oil, and the balance at least one oil selected from the group consisting of linseed oil, sunflower. oil, grape seed oil, seal oil and fish oil, at least partially polymerizing the admixed oils, admixing the at least partially polymerized oils with a mineral core forming material, forming the admixture and completing the polymerization.

9. A process for the manufacture of non-deforming cold-setting cores and moulds by the steps of admixing above about 7% of Boleko oil, at least about 2% of. at

least one oil selected from the group consisting of wood oil, oiticica oil' and dehydrated castor oil, and the balance at least one oil selected from the group consisting of linseed oil, sunflower oil, grape seed oil, seal oil and fish oil, at least partially polymerizing the admixed oils, admixing the at least partially polymerized oils with a mineral core forming material and an oxidation accelerator from the group consisting of chlorites, carbonates, metallic oxides, lead acetate and calcium chlorite.

10. A non-deforming cold-setting article comprising a mineral core and mould forming material bonded together with a polymerized admixture of at least about 2% of a triglyceride having conjugate lines of double bond linkage, above about 7% of a triglyceride having an acetylene type bond and the balance at least one triglyceride which does not fall within either of the two preceding classes.

11. A non-deforming cold-setting article comprising a mineral core and mould forming material bonded together with a polymerized admixture of at least about 7% of Boleko oil, at least about 2% of at least one oil selected from the group consisting of wood oil, oiticica oil and dehydrated castor oil and the balance at least one oil from the group consisting of linseed oil, grape seed oil, sunflower oil, seal oil and fish oil.

12. A binding oil for cores and moulds and the like comprising at least about 2% of a triglyceride having conjugate lines of double bond linkage, above about 7% of a triglyceride having an acetylene type bond and the balance at least one triglyceride which does not fall within either of the two preceding classes.

13. A binding oil for cores and moulds and the like comprising above about 7% of Boleko oil, at least about 2% of at least one oil from the group consisting of wood oil, oiticica oiland dehydrated castor oil and the balance at least one oil from the group consisting of linseed oil, grape seed oil, sunflower oil, seal oil and fish oil.

14. A binding oil for cores and moulds and the like comprising about two percent to fifty percent of at least one oil from the group consisting of wood oil, oiticica oil and dehydrated castor oil, about five percent to eightyseven percent of at least one oil from the group consisting of linseed oil, grape seed oil, sunflower oil, seal oil and fish oil and about ten percent to fifty-five percent of Boleko oil.

References Cited in the file of this patent UNITED STATES PATENTS 2,219,862 Bradley Oct. 29, 1940 2,228,154 Priester Jan. 7, 1941 2,248,965 Corker-y July 15, 1941 2,272,483 Sheely Feb. 10, 1942 2,274,618 Reny Feb. 24, 1942 2,280,082 Priester Apr. 21, 1942 2,300,090 Auer Oct. 27, 1942 2,556,335 Moser June 12, 1951 OTHER REFERENCES Von Fisher: Paint and Varnish Technology (1948), Reinhold Publishing Corp, 330 West 42nd St., N. Y. 18, N. Y. (pages 26 and 27 relied on).

Chatfield: Varnish Constituents (1953), London, Leonard Hill Limited, 9 Eden St., N. W., London, Eng land (pages 90 and 91 relied on). 

1. A PROCESS FOR THE MANUFACTURE OF NON-DEFORMING COLD-SETTING CORES AND MOULDS BY THE STEPS OF ADMIXING AT LEAST ABOUT 2% OF AN OIL HAVING CONJUGATE LINES OF DOUBLE BOND LINKAGE, ABOVE ABOUT 7% OF AN OIL HAVING AN ACETYLENE TYPE BOND AND THE BALANCE AN OIL COMPATIBLE WITH THETHE TWO FOREGOING OILS WHICH DOES NOT FALL WITHIN THE TWO PRECEDING CLASSES, POLYMERIZING SAID MIXED OILS, ADMIXING THE AT LEAST PARTIALLY POLYMERIZED OILS WITH A MINERAL CORE FORMING MATERIAL, FORMING THE RESULTING ADMIXTURE AND COMPLETING THE POLYMERIZATION OF ANY UNPOLYMERIZED OILS. 